Introduction
Malaria in Haiti is a significant public health concern, with an estimated 80% of the population at risk of infection.1 Plasmodium falciparum is the predominant malaria parasite species in Haiti, and it accounts for more than 98% of all confirmed malaria infections.2 The transmission of malaria in Haiti is tightly linked with rainfall patterns,3 with the peak transmission season occurring between November and January.4 The treatment of malaria in Haiti is based on chloroquine (CQ) given at a total dose of 25 mg base per kilogram body weight over a 3-day period. Recently, the treatment policy was revised to incorporate a single dose of primaquine2 for malaria patients found to harbor gametocyte stages that are transmissible to mosquitoes.
Despite being rendered ineffective for treating malaria in many endemic areas because of resistance, CQ is still used in Haiti because of the apparent sensitivity of the P. falciparum strains in Haiti. The use of CQ might have been continued based on drug sensitivity studies conducted in the 1980s that found P. falciparum to be sensitive to CQ.5,6 However, the recent findings of genetic markers of CQ resistance in P. falciparum7,8 might indicate a change in sensitivity and emergence of CQ resistance in Haiti. However, there are no recent in vivo CQ efficacy data. To provide up to date information about the efficacy of CQ in the treatment of P. falciparum malaria infections, this study evaluated the treatment outcomes in patients with uncomplicated P. falciparum undergoing CQ therapy. The data obtained in this study might be useful in guiding future malaria treatment policy in Haiti.
Methods
Ethical approval.
This study was approved by the Haiti Ethical Review Board, the University of Florida Institutional Review Board, and the Office of Research Protections, United States Army Medical Research and Material Command (USAMRMC).
Study site.
This study was conducted between September of 2011 and December of 2012 at two clinics in Haiti: (1) Hospital Saint Croix in Leogane, a regional reference hospital managed by the Episcopal Church of Haiti and (2) the Family Medical Health Ministries Medical Center (Blanchard Clinic), which is located in Port-au-Prince in Blanchard (Terre Noire) 1 mile northwest of the Port-au-Prince International Airport (Figure 1).
Map showing the communes and the clinics where the study was conducted.
Citation: The American Society of Tropical Medicine and Hygiene 92, 3; 10.4269/ajtmh.14-0302
Map showing the communes and the clinics where the study was conducted.
Citation: The American Society of Tropical Medicine and Hygiene 92, 3; 10.4269/ajtmh.14-0302
Map showing the communes and the clinics where the study was conducted.
Citation: The American Society of Tropical Medicine and Hygiene 92, 3; 10.4269/ajtmh.14-0302
Identification and enrollment of patients in the follow-up study.
The participants in this study were identified from patients seeking treatment at the clinics. Febrile patients presenting with malaria symptoms were tested by rapid malaria diagnostic tests (CareStart, AccessBio, Somerset, NJ) and followed by standard microscopy for the confirmation and quantification of P. falciparum parasitemia in positive cases. To participate in the study, patients had to meet the following inclusion criteria: (1) between the ages of 2 and 100 years old, (2) not severely malnourished (defined as a child whose weight for height is below 3 standard deviations or less that 70% of the median of World Health Organization [WHO] reference values), (3) have microscope slide-confirmed infection with P. falciparum malaria with a parasite density of at least 1,000 asexual parasites/μL blood, (4) absence of general danger signs among children < 5 years old and other signs of severe complicated malaria (e.g., inability to drink or breastfeed, vomiting everything, recent history of convulsions, lethargy or unconsciousness, and inability to stand), (5) absence of hypersensitivity reactions to CQ, and (6) no history of previous antimalarial use within the previous 2 weeks. The exclusion criteria included (1) pregnant or lactating women, (2) existence of underlying chronic severe illness (e.g., human immunodeficiency virus [HIV] and hepatic diseases), and (3) refusal to give consent to participate in the study. The details of the study protocol were explained to the prospective participants or the guardians of children in a language that they could understand (Kreyol), and those giving consent were requested to sign an informed consent form to affirm their agreement to participate in the follow-up study. All malaria-positive subjects were treated with 25 mg CQ per kilogram body weight according to the standard protocol at the clinics under the direct supervision of the study site physician. The number of participants enrolled and followed-up is illustrated in Figure 2.
Patient identification, enrollment, and follow-up schematic. d = Day.
Citation: The American Society of Tropical Medicine and Hygiene 92, 3; 10.4269/ajtmh.14-0302
Patient identification, enrollment, and follow-up schematic. d = Day.
Citation: The American Society of Tropical Medicine and Hygiene 92, 3; 10.4269/ajtmh.14-0302
Patient identification, enrollment, and follow-up schematic. d = Day.
Citation: The American Society of Tropical Medicine and Hygiene 92, 3; 10.4269/ajtmh.14-0302
Clinical study.
After enrolling in the study on day 0, the participants were followed up on days 1, 2, 3, 7, 14, 21, 28, 35, and 42. CQ (Ranbaxy Pharmaceuticals Inc, Jacksonville, FL) treatment was given at 10 mg per kg body weight on day 0, 10 mg per kg body weight on day 1, and 5 mg per kg body weight on day 2. Patients were requested to come back on the pre-appointed days for clinical monitoring and assessment of parasite clearance by microscopy. In addition, community health workers followed up with the participants at their homes. P. falciparum parasitemia was assessed by standard microscopy techniques by counting the number of asexual P. falciparum parasites per 2,000 leukocytes.9 On each follow-up day, the temperature of the subjects was recorded, and the hemoglobin concentration was measured using a hemoglobin meter (Hemacue Hb 201; Angelholm, Sweden).
Treatment outcomes.
The WHO standard classification of treatment outcomes in low-malaria transmission settings10 was used as shown in Table 1. The primary treatment outcomes were assessed on day 28. The treatment outcomes were also assessed on day 7 following the simplified WHO standard 7-day in vivo field test as used by Duverseau and others5 and day 14 as suggested by WHO.10
Treatment endpoints and patient condition as described in the WHO manual for the assessment and monitoring of antimalaria drug efficacy for the treatment of uncomplicated P. falciparum10
| Treatment outcome | Patient condition |
|---|---|
| ETF | Development dangers signs or severe malaria on day 1, 2, or 3 after drug treatment in the presence of parasitemia |
| Malaria parasite count on day 2 is higher than on day 0, irrespective of axillary temperature of the patient | |
| Axillary temperature ≥ 37.5°C on day 3 in the presence of parasitemia | |
| Parasitemia on day 3 is ≥ 25% of the count on day 0 | |
| LTF | Development of danger signs or severe malaria in the presence of parasitemia on any day from day 4 to 14 after treatment without previously meeting any of the criteria for ETF |
| Presence of parasitemia on any day from day 4 to 28 and a measured axillary temperature > 37.5°C (or fever) without previously meeting any of the criteria of ETF | |
| LPF | Presence of parasitemia on any day from day 7 to 28 and axillary temperature of < 37.5°C without previously meeting criteria for LTF |
| ACPR | Absence of parasitemia on day 28, irrespective of axillary temperature, without previously meeting any of the criteria of ETF, LTF, or ACPR |
ACPR = adequate clinical and parasitological response; ETF = early treatment failure; LTF = late clinical failure; LPF = late parasitological failure.
Statistical analysis.
Mean values of age, hemoglobin content, and parasitemia of enrolled patients were computed on SPSS version 21 software. Only patients who completed the study with no major protocol violation were used in the analysis of the treatment outcomes. Those lost to follow-up or who withdrew consent were excluded from the analysis.
Results
Low P. falciparum malaria infection rates in febrile patients.
In total, 1,277 symptomatic patients presenting with malaria-like fevers were tested for P. falciparum infection (Table 2). The positivity rate for P. falciparum by slide-confirmed microscopy was 9.5% (121 of 1,277). There was seasonal variation in malaria-like symptoms and P. falciparum malaria cases, with peak numbers of cases observed in October and January, respectively (Table 2).
Monthly data of patients with malaria-like fevers screened for P. falciparum infection at the two clinics in Haiti
| Year and month | Hospital Saint Croix | Blanchard Clinic | Total number of cases | |||
|---|---|---|---|---|---|---|
| Fever | Malaria | Fever | Malaria | Fever | Malaria | |
| 2011 | ||||||
| September | 34 | 1 | 11 | 3 | 45 | 4 |
| October | 43 | 3 | 13 | 5 | 56 | 8 |
| November | 103 | 13 | 11 | 7 | 114 | 20 |
| December | 105 | 8 | 25 | 18 | 130 | 26 |
| 2012 | ||||||
| January | 101 | 6 | 4 | 3 | 105 | 9 |
| February | 74 | 5 | 3 | 1 | 77 | 6 |
| March | 70 | 4 | 15 | 3 | 85 | 7 |
| April | 81 | 4 | 24 | 1 | 105 | 5 |
| May | 103 | 4 | 28 | 7 | 131 | 11 |
| June | 135 | 2 | 15 | 2 | 150 | 4 |
| July | 59 | 2 | 13 | 3 | 72 | 5 |
| August | 81 | 0 | 11 | 2 | 92 | 2 |
| September | 33 | 0 | 10 | 2 | 43 | 2 |
| October | 54 | 1 | 18 | 11 | 72 | 12 |
| Total | 1,076 | 53 | 201 | 68 | 1,277 | 121 |
Malaria infection was detected by rapid detection kit and confirmed by microscopy.
Patient characteristics at enrollment and follow-up.
Eighty-eight percent (107 of 121) of malaria-positive patients identified by microscopy gave consent and were enrolled to participate in the study. The mean age of the enrolled patients was 31.7 years (range = 11–85 years). The mean temperature at enrollment was 37.9°C, whereas the hemoglobin content was 13.1 g/dL. The mean parasite density in enrolled patients at day 0 was 1,967.29 ± 131.5. The mean temperature reduced to 37.2°C by day 42, whereas the hemoglobin content remained stable over all subsequent follow-up days; 60 patients successfully completed the 42-day follow-up period, whereas 47 patients withdrew consent or were lost to follow-up (Table 3). The number of patients who withdrew consent or were lost to follow-up was highest in the first 1 week and then stabilized with time (Table 3). The number of patients with assessed clinical endpoints who completed follow-up is presented in Table 4.
The characteristics of patients diagnosed with P. falciparum on day 0 of enrollment grouped by the treatment outcome observed in the study
| Follow-up day | ||||
|---|---|---|---|---|
| 7 | 14 | 28 | 42 | |
| Completion of study procedures | 88 | 77 | 68 | 60 |
| Voluntary withdrawals/loss to follow-up (weekly withdrawals/loss to follow-up) | 19 (19) | 30 (11) | 39 (9) | 47 (8) |
| Total number of enrolled patients | 107 | 107 | 107 | 107 |
Therapeutic outcomes in malaria patients undergoing CQ treatment in Haiti
| Study endpoint | Day 7 | Day 14 | Day 28 | Day 42 |
|---|---|---|---|---|
| Early treatment failure | 0 | 0 | 0 | 0 |
| Late clinical failure | 0 | 0 | 0 | 0 |
| Late Parasitological Failure | 7 | 7 | 7 | 7 |
| Adequate clinical and parasitological response | 81 | 70 | 61 | 53 |
| Total number of patients | 88 | 77 | 68 | 60 |
| Treatment failure rate (%) | 7.9 | 9.1 | 10.3 | 11.6 |
| Parasite cure rate/clearance rate (%) | 92.1 | 90.9 | 89.7 | 88.4 |
The treatment outcome endpoints were assessed on days 7, 14, 28, and 42 as described in Methods.
Parasitological outcomes of malaria patients treated with CQ.
The mean parasite density declined rapidly after treatment as shown in Figure 3. Seven patients did not clear their malaria infections but were clinically asymptomatic, and therefore, they were considered late parasitological failures (LPFs). These patients were positive until day 42, but their parasitemia levels continued to steadily decrease. On day 28, 91.0% (95% confidence interval [95% CI] = 84.20–97.90) of patients had no detectable parasitemia by microscopy. These patients remained clear of malaria parasites until the end of the extended follow-up period (day 42). In the simplified WHO in vivo field test, 92.1% (95% CI = 86.4–97.7) of patients cleared their parasitemia by day 7, and following the WHO-suggested 14-day follow-up period,10 91% (95% CI = 84.5–97.3) of patients were aparasitemic.
The parasitemia rates in P. falciparum malaria patients undergoing CQ therapy in Haiti.
Citation: The American Society of Tropical Medicine and Hygiene 92, 3; 10.4269/ajtmh.14-0302
The parasitemia rates in P. falciparum malaria patients undergoing CQ therapy in Haiti.
Citation: The American Society of Tropical Medicine and Hygiene 92, 3; 10.4269/ajtmh.14-0302
The parasitemia rates in P. falciparum malaria patients undergoing CQ therapy in Haiti.
Citation: The American Society of Tropical Medicine and Hygiene 92, 3; 10.4269/ajtmh.14-0302
Discussion
Our study observed high treatment success rates (adequate clinical and parasitological responses) in malaria patients after CQ therapy, although a few patients did not respond to treatment and were categorized as treatment failures. Molecular analysis of these seven cases did not find the pfcrt K76T mutation11 that is widely associated with CQ resistance. It is not clear why the patients remained chronically parasitemic, because we did not test for reinfection or recrudescence. In addition, we were not able to test for the blood concentration levels of CQ in the patients, and therefore, we do not know if these patients rapidly metabolized and eliminated the antimalarial medicine. The P. falciparum densities in the patients who participated in the study were generally low (approximately 0.6% parasitemia). On CQ therapy, a rapid decline in the parasite densities was observed within the first 3 days, suggesting high sensitivity to CQ. Our findings support the notion that high CQ sensitivity of P. falciparum malaria exists in Haiti, but the status of resistance to CQ is inconclusive. There is a great need to continue monitoring efforts of the emergence of resistance to antimalarial drugs that may be in use in Haiti.
The drastic decline of parasitemia on treatment with CQ observed in many patients in our study is suggestive of widespread sensitive malaria strains in Haiti. In areas with CQ-sensitive malaria, similar rapid declines in parasitemia have been observed. In a CQ efficacy trial in Honduras, where CQ-sensitive P. falciparum is prevalent, the parasitemia rapidly reduced after CQ treatment, and by the third day, less than 10% of the malaria patients had malaria parasites in their blood.12 In our study, the high proportion of patients who were successfully treated with CQ supports the assertion that malaria parasites in Haiti are sensitive. In the earlier in vivo CQ efficacy study conducted by Duverseau and others5 in Haiti, 81% of the patients had no detectable parasitemia in their blood by the seventh day. Our study observed a high percentage (92%) of patients with no detectable parasitemia in their blood by the seventh day, mirroring the findings by Duverseau and others.5 Moreover, the proportion of patients remaining positive after CQ treatment reduced very rapidly within the first week (57% on day 1, another 25% on day 3, and another 18% on day 7), which is very consistent with treatment efficacy data from areas reported with CQ-sensitive P. falciparum, like Honduras.
Despite observing a few cases that did not respond to treatment, the evidence for CQ resistance is not clear cut in our study. Molecular testing did not find the K76T mutation in the Pfcrt gene11 in these seven patients. It is not exactly clear why these patients did not respond to treatment, although the patients were compliant with the treatment and follow-up protocol and completed their medications under direct supervision of the medical doctors. However, it is possible that host factors (such as differences in individual pharmacokinetics) might have led to suboptimal CQ concentrations in the blood, but we were unable to test for serum levels of the CQ in these patients. Although we did not test for reinfections or recrudescent parasites because of a lack of sufficient samples, these are unlikely to be the case, because the parasite densities in these seven patients decreased rapidly and did not increase at any point during the follow-up, as would be expected with reinfections or recrudescent parasites.
The high loss to follow-up and withdrawal rates of the participants impacted this study. The extension of the follow-up period from 28 to 42 days caused an increase in the number of patient withdrawals and follow-up loss. Only patients with no major protocol violation were included in the analysis; those lost to follow-up or who withdrew consent were excluded from the analysis. Therefore, overall cure rates dropped from 92.1% on day 7 to 89.7% on day 28, which is largely attributed to patient loss to follow-up. The losses observed in our study were somewhat higher at 42 days than has been observed in other studies.10 However, such high dropout rates are to be expected in study areas, such as Haiti, where clinics can be far away from patients.13 Although a tremendous amount of effort was put into minimizing the dropout rates (for example, hospital staff would visit patients at their homes, patients were given reimbursements for food and travel costs, and overnight accommodations were also available for the enrolled patients), in the end, the patients' right to withdraw their consent at any time was paramount, and their decisions had to be respected in accordance with the consent documents that they signed.
In conclusion, our study presents data that suggest that CQ may still have an important role to play in the treatment of uncomplicated P. falciparum in Haiti but are inconclusive about CQ resistance because of the unresolved status of the seven cases that did not respond to treatment. Because we did not to detect the pfcrt K76T mutation, the CQ resistance status of these seven patients is unresolved; we did not determine the presence of other single-nucleotide polymorphisms (SNPs) in the Pfcrt gene that have also been associated with CQ resistance,14 and therefore, the CQ resistance issue in Haiti remains an open question. In addition, there are still unanswered questions surrounding the bioavailability of CQ (CQ serum levels) in the patients with parasitological failure. Although the patients were complaint with the study protocols and procedures, the individual differences in drug metabolisms may have influenced the effectiveness of CQ for malaria treatment in these patients. It is also very likely that a low-malaria transmission setting, like Haiti, is likely to slow the spread of CQ resistance.15 Finally, we urge that surveillance activities for antimalarial drug resistance be increased in Haiti and whenever possible, that malaria patients undergoing treatment be followed up or requested to return for follow-up visits. Additionally, in vitro sensitivity testing should be performed if resources allow, and sample collection through dried blood spots should be done to enable future investigations on molecular markers for antimalaria drug resistance.
ACKNOWLEDGMENTS
We acknowledge the efforts of many people in Haiti who made this study a success: the Episcopal Church of Haiti for allowing the study to be done at Hospital Saint Croix, Christianville Foundation in Gressier, Haiti, Fish Ministries Haiti, and Family Health Ministries. We also thank the other members of the Hospital Saint Croix staff who helped and made this study a success, including Delva Carole, Benoit Phara, and Pierre Michel, and staff members of Family Health Ministries, including Ms. Aliette Lapaix and Mr. Sterling Ulrick.
- 1.↑
MSPP, 2009. Plan Strategique National de lutte Contre la malaria - Ministere de la Sante Publique et de la Population Haiti (Coordination des programmes nationaux de malaria et filariose lymphatique). p. 54. Ministere de la Sante Publique et de la Population, Haiti.
- 4.↑
Bonnlander H, Rossignol AM, Rossignol PA, 1994. Malaria in central Haiti: a hospital-based retrospective study, 1982–1986 and 1988–1991. Bull Pan Am Health Organ 28: 9–16.
- 5.↑
Duverseau YT, Magloire R, Zevallos-Ipenza A, Rogers HM, Nguyen-Dinh P, 1986. Monitoring of chloroquine sensitivity of Plasmodium falciparum in Haiti, 1981–1983. Am J Trop Med Hyg 35: 459–464.
- 6.↑
Magloire R, Nguyen-Dinh P, 1983. Chloroquine susceptibility of Plasmodium falciparum in Haiti. Bull World Health Organ 61: 1017–1020.
- 7.↑
Londono BL, Eisele TP, Keating J, Bennett A, Chattopadhyay C, Heyliger G, Mack B, Rawson I, Vely JF, Desinor O, Krogstad DJ, 2009. Chloroquine-resistant haplotype Plasmodium falciparum parasites, Haiti. Emerg Infect Dis 15: 735–740.
- 8.↑
Gharbi M, Pillai DR, Lau R, Hubert V, Khairnar K, Existe A, Kendjo E, Dahlstrom S, Guerin PJ, Le Bras J, 2012. Chloroquine-resistant malaria in travelers returning from Haiti after 2010 earthquake. Emerg Infect Dis 18: 1346–1349.
- 9.↑
PAHO, 2003. Practical Guide for In Vivo Antimalarial Drug Efficacy Studies in the Americas. p. 23. Pan American Health Organization, OPS/DPC/CD/240/03.
- 10.↑
WHO, 2003. Assessment and Monitoring of Antimalarial Drug Efficacy for the Treatment of Uncomplicated Falciparum Malaria. Geneva: World Health Organization.
- 11.↑
Elbadry MA, Existe A, Victor YS, Memnon G, Fukuda M, Dame JB, Yowell CA, Okech BA, 2013. Survey of Plasmodium falciparum multidrug resistance-1 and chloroquine resistance transporter alleles in Haiti. Malar J 12: 426.
- 12.↑
Mejia Torres RE, Banegas EI, Mendoza M, Diaz C, Bucheli ST, Fontecha GA, Alam MT, Goldman I, Udhayakumar V, Zambrano JO, 2013. Efficacy of chloroquine for the treatment of uncomplicated Plasmodium falciparum malaria in Honduras. Am J Trop Med Hyg 88: 850–854.
- 13.↑
Ruebush TK 2nd, Marquino W, Zegarra J, Neyra D, Villaroel R, Avila JC, Diaz C, Beltran E, 2003. Practical aspects of in vivo antimalarial drug efficacy testing in the Americas. Am J Trop Med Hyg 68: 391–397.
- 15.↑
Hastings IM, Watkins WM, 2005. Intensity of malaria transmission and the evolution of drug resistance. Acta Trop 94: 218–229.